Fluid flow surge dampening system



Sept. 10, 1963 R. s. wAsHBURN FLUID FLow SURGE DAMPENING SYSTEM Filed Feb. 8, 1961 United States Patent O 3,103,234 FLUID FLOW SURGE DAMPENING SYSTEM Robert S. Washburn, Beloit, Wis., assigner to Beloit Iron Works, Beloit, Wis., a corporation of Wisconsin Filed Feb. 8, 1961, Ser. No. 87,837 7 Claims. (Cl. 13S-30) ,desurging devices have been used or suggested by the prior art in many fields, and particularly in relatively high press-ure fluid pipe lines wherein sudden pressure surges may cause damage to the equipment. In the case of paper making machines, the fan pump subject to -surging or pulsation and this is undesirable for the reason that stock delivered by the fan pump should be introduced into the head box rwith a minimum of surging or other irregularity in the flow rate. The stock used in paper machines is a suspension of fibers in Water, and because of the presence of the fibers (even though in dilute concentrations) the handling of the stock presents la number of problems. Conventional desurging devices are not effective with paper stock because of the presence of the fibers therein which tend to foul up sensitive control de- .vices or other functioning components.

The instant invention provides a surge ldampening device which is free from the problems of conventional prior art devices of this type resulting from the presence of fibers in the stock. In addition, the instant invention provides a simple, sturdy, readily assembled and reliable device which effectively controls for dampens pressure surges in a pipe or duct handling fluid under pressure v which must be isolated or Iwhich contains components which must be isolated from control. elements.

It is, therefore, an important object of the instant invention to provide an improved surge dampening device, and more particularly, yto provide an improved surge dampening device for the handling yof fluids which must be isolated from control components. l

It is `a further object of the instant invention to` provide a surge dampening device for use in -a pipe 4line to minimize sur-ges of pressure therein, said devicevcornprising, in combination, concentric resilient fluid-impervious sleeves adapted to .be mounted in said pipe line and to yieldingly respond to sudden surges lof pressure therein, the mean pressure in the pipe being subject togradual variations, a perforated concentric mandrel interposed between said sleeves and isolated from the pipe fluid, and cushioning compartment means encircling said sleeves 4for exposing the exterior thereof to gas under substantial-ly the -mean pipe pressure to dampen such pressure surges.

Other and further objects, features and advantages of ICC Certain essential functional elements of the device 10 include a first resilient sleeve member 11 mounted in the pipe line and exposed directly to the fluid flowing therethrough in the area 12. The sleeve 11 is a generally cylindrical member formed of resilient solid elastomer, such `as rubber or synthetic resinous elastomer Iand itis adapted to yieldingly respond to sudden surges of pressure in the fluid flowing in the pipe line and conduit region 12. The mean or average pressure of the fluid in the conduit 12 is subject to gradual variations, as Well as the sudden surges of excessively high or excessively low pressure deviating-'from the mean pressure. 'Ille left hand flange element .10a has a threaded recess 10e therein 'which engages the externally threaded portion 13a of a ring 13 -to mount the same. The ring .13 has a tapered lip 13b receiving one end 11a of the sleeve i11, which has an :annular enlargement 11b at the extremity thereof. An annular clamp 14 hasinterior threads 14a engaging the exterior threaded portion 13a of the ring 13 for clampin-g the enlarged end portion 11b ofthe sleeve 11 into sealing engagement with the ring 13. At the opposite end of the assembly 10 another ring 23 is threadedly received land mounted in la recess 23a in the right hand flange portion 10b; `and la second annular clamp 24 threadedly enlga-ging the ring 23 sealingly clamps an enlargement 11C at the opposite end of the sleeve 11. Reading from left to rig-ht the elements 10a, 13, 11, 23 and 10b form a substantial continuation of the fluid flow conduit 12,

`which may be used to replace a small section in a confin turn is :clamped against the annular clamp 24 by a fourth ring 43 threadedly engaging the annular clamp 24 at 24h. Seal rings are provided in conventional manner at 25 between the ring 23 and the flange element 10b, `at 26 between the ring 43 (the annular clamp 24) and the flange 10b, and :at 27 between the ring 33 (the `annular 45 clamp `14) `and the flange element 10a.

The sleeve 31 is also formed of resilient elastomeric material such as rubber and it may be formed of the 'same material as the first sleeve 11. The sleeves 31 and 11 are thus mounted and define therebetween .an annular chamber A, which retains fluid under pressure. ln the chamber A there is a perforated mandrel Sti that is concentric with the sleeves 11 and-31 and encircles the inner sleeve 11. The mandrel 50 is threadedly received .at one end in `an annular recess 14e in the annular clamp 14 and at the opposite end in an annular recess 24c in the `annular clamp 24. The mandrel 50 is preferably formed of a suitable rigid structural material and it may consist of perforate metal, porous ceramic for any rigid septum. As here shown the mandrel 50 is a metal sleeve having `a plurality ofi throttling orifices 51, 51 of predetermined diameter and spacing to effect the friction losses in the fluid in the chamber A passing therethrough and a surge dampening effect which will be described in detail. The nature of the fluid permeable layer or mandrel 50 coupled with the fluid present in the chamber A will determine to a substantial extent the surge dampening effect that is obtained by the use of this portion of the overall assembly 1li,A by virtue of the friction factors involved (Le. for such viscous dampening).

The instant mandrel Sti is also :adapted for variable porosity or fluid permeability. In the condition shown in thel drawing, the sizel and spacing of the orifices 51 will determine the fluid permeability. 'I'he mandrel S0 is, however, provided with a rather narrow annular central recess 50a which extends throughout the perforated area thereof and opens at the right hand end 501:. This annular recess Sila may be maintained substantially empty, or it may be partially or completely filled with a porous sleeve which will effect a diffe-rent overall porosity `for the mandrel 50. As shown a-t the right hand end 50h primarily for purposes of example, ashort porous sleeve 52 may be used to influence the flow of fluid through some or all of the orifices, depending upon the size of the sleeve 52. In the embodiment shown, the sleeve 52 would effect the porosity of only a porytion of the mandrel 50, but a sleeve corresponding in design to the sleeve 52 but substantially equivalent in length to the overall annular recess 50a could be used to replace the sleeve 52 and thus effect an entirely different porosity for the overall mandrel S0. The mandrel 50 divides the chamber A into an inner annular chamber 53 `and an outer annular chamber 54 between the sleeves 11 and 31.

In assembling the instant device, the annular clamps 14 and 2.4 are threaded onto opposite ends of the selected perforate mandrel 50, and the sleeves 11 and 31 are slipped over this assembly 14, 50, 24. The rings 13 and 33 are then threaded onto lthe annular clamp 14 to seal the left hand end so that the sleeves 11 and 3'1 and Ithe rings 23 and 43 are threaded onto the other annular clamp 24 to seal the opposite ends of the sleeves 11 and 31. Prior to threading the annular clamp 24 onto the mandrel 50, a selection of the type of permeability control sleeves 52 (if one is to be used) is made and Athe same is inserted in the mandrel 50. After the rings 23 and 43 have been securedto complete the mounting of the sleeves 11 and 31, `the chamber A is filled with a fluid, which may be a gas under pressure such as air, but which is preferably a liquid of sufficient viscosity (i.e. having suitable friction factors) to accomplish the desired viscous dampening in the chamber A during operation. The fluid may be fed into the chamber A through a suitable passageway 24d in the annular clamp 24, and the passageway 24d may then be sealed with a plug 24e.

A sudden surge ofi pressure in the ow conduit 12 nds initial response in the interior sleeve 11 which yields resiliently by moving outwardly. This in turn causes fluid in the inner side 53 of the chamber A to flow through the orifices 51 and the mandrel 50 (with consequent viscous dampening) which results in a somewhat dampened surge against Ithe interior of the outer sleeve 31. The outer sleeve 31, in turn, yields in response to this surge.

The exterior wall 31d of the outer sleeve 31, however, denes with a cylindrical housing 60 -a cushioning compartment CB. The left hand iiange element u of the device 10 is provided with a hollow section 10c which receives the annular clamp 14 and ring 33, and a secondary flange section 10d extending upwardly Itherefrom which cooperates with an annular ange 60d on the left hand end of the cylindrical housing 60. The cylindrical housing 60 is mounted via the flange 10d-60d with suitable bolts as `at `61 `and `a seal at 62. At the iight hand side of the housing 60, Ithere is Aalso provided an annular lip 60e mounting a seal 63 for engagement with the exterior of the ring 43 to complete the 'sealing off of the cushioning compartment B. Fluid under pressure is maintained in the cushioning compartment `B and this Huid is preferably a gas such as compressed Vair (although it may be a liquid such .as water). In the pref-erred embodiment, the viscous dampening chamber A contains a liquid such as distilled water, ethylene glycol, oils, or the like which accomplish the desired viscous dampening during Iflow through the orifices 51; whereas the cushioning ychamber B contains a gas under pressure such -as air. Air under pressure is fedfrom a source S through a control valve V and into an inlet 64 in the cylindrical housing 60, in a conventional arrangement shown diagrammatically. In the preferred embodiment the air pressure in the cushioning compartment B is maintained substantially equivalent to the mean fluid pressure in the conduit S12, via control of the valve V. In this way the sleeves 11 `and 31 are maintained in more or less of an equilibrium position in between pressure surge-s in the ow conduit 1'2, but during pressure surges, wherein the pressure varies from the mean pressure, movement of the sleeves 11 and 31 is effected. The left hand flange element 10a is provided with a conventional pressure sensing aperture 65, whereby the pressure in the dlow conduit 12 is continuously sensed. Preferably the pressure sensing device indicated diagrammatically at 66 does not actu-ally receive liquid from the conduit, but merely senses the pressure thereof via a diaphragm or other suitable means. The pressure signal thus obtained is a compressed air signal in the line `66, which is` also provided with capillary passages at 67 (or other conventional means for damping pressure surges by frictional effect or otherwise, while 'still transmitting the gradual variations in the mean pressure in the conduit 12). The damping system 67 thus vpermits the transmission of a iiuid pressure signal from the flow lline 12 via such damping system 67 Ato the control valve V which signal received by the valve V is directly responsive to variations in the mean pressure in the conduit 12. The control valve V, in turn, controls the uid pressure in the cushioning compartment B so as to maintain the same substantially equivalent to the mean fluid pressure in the conduit 12 at any given time.

It will be appreciated that the various elements of the system 64, 65, 66, 67 for the control valve V and the compressed air source S are conventional and these components are indicated diagrammatically. The essential diunotion thereof is to maintain the cushioning compartment diuid pressure responsive (and preferably equivalent) to the mean conduit fluid pressure at any given time. This is accomplished by the use of the fluid pressure sensing means 65, 66, 67 connectedA to the conduit 12 and the control fvalve V for transmitting to the control valve V responses to variations in the mean pressure and the pipe 12.

In summary, the instant invention comprises a surge dampening device 10 [for ruse in a conduit 12 to dampen sudden surges of fluid pressure therein, the device 10 comprising a member 11 movable in response to such surges interposed between the conduit 12 and a chamber A and subject to the conduit iiuid pressure on one side and a chamber il-uid pressure on the other side, an element 31 movable in response to pressure surges interposed bet-ween the chamber A and a compartment B and subject to the chamber fluid pressure on one side and a compartment uid pressure Kon the other side, a fluid permeable layer 50 interposed between said member 11 and said element 31 dividing said chamber A into two enclosures for throttling chamber fluid pressure from one enclosure to the other, and valve means V maintaining the compartment iinid pressure responsive to the mean conduit fluid pressure.

,It will be understood that modifications and variations may be effected without departing from the spirit and scope of :the novel concepts olf the present invention.

I claim as my invention:

rl. A surge damping device for use in a conduit to dampen sudden changes of fluid pressure therein, said deviceV comprising, in combination, a fluid-impervious member movable in response to such surges interposed between the conduit and a chamber and directly exposed to iiuid flowing in the conduit so as to be subject to the conduit uid pressure on one side and a chamber fluid pressure on the other side, a fluid-impervious element movable in response to pressure surges interposed belayer having a plurality of throttling orifices interposed between said member and said element dividing said chamber into two enclosures -for throttling chamber fluid flow [from one enclosure to the other, valve means maintaining the compartment fluid pressure responsive to a dampened signal, means sensing the conduit fluid pressure and sending out a signal in response thereto, and means delaying said signal to dampen abrupt variations therein and sending a :dampened signal to said valve means.

2. A surge dampening device for use in a pipe line to minimize surges of pressure therein, said device comprising, in combination, a first resilient fluid impervious sleeve member adapted to be mounted in said pipe line directly exposed to fluid flowing therein and to yieldingly respond to sudden surges of pressure therein, the mean pressure in the pipe being subject to gradual variations, a perforated mandrel having la plurality of throttling oriiices encircling said first sleeve, a second resilient fluid impervious sleeve member encircling said mandrel and maintaining said mandrel in a separate body of fluid, cushioning compartment means encircling said second sleeve dor maintaining gas under pressure to dampen such pressure surges, control means ffor maintaining the gas pressure in said compartment substantial-ly equivalent to the mean pressure in the pipe, means sensing the pipe line fluid pressure and sending out a signal in response thereto, and means delaying said signal to dampen abrupt variations therein and sending a dampened signal to actuate said control means.

3. A surge dampening device for use in a pipe line to minimize surges of pressure therein, said device comprising, in combination, Ia first resilient fluid-impervious sleeve member adapted to be mounted in said pipe line to form a continuation thereof directly exposed to fluid flowing therein and to yieldingly respond to sudden surges olf pressure therein, the mean pressure in the pipe being subject to `gradual variations, a perforated mandrel having a plurality of throttling orifices encircling said first sleeve, a second resilient fluid-impervious sleeve member encircling said mandrel and maintaining said mandrel in a separate body of fluid, whereby such pressure surges effect flow of fluid in said body through said mandrel and yieldi-ng response by said second sleeve, cushioning compartment means encircling said second sleeve for maintaining ygas .under pressure to dampen such pressure surges, a source of gas under pressure, sensing means connected to .the pipe line rior sending a fluid pressure signal responsive to pressure in the pipe line, reservoir means delaying and damping the fluid pressure signal from said sensing means and sending a dampened fluid pressure signal, and a control valve -for said source responsive to the dampened fluid pressure signal dor maintaining the gas pressure in said compartment substantially equivalent to the mean pressure in the pipe.

4. A surge dampening device for use in a pipe line to minimize surges of pressure therein, said device comprising, in combination, la first resilient fluid-impervious sleeve member adapted to be mounted in said pipe line to form a continuation thereof directly exposed to fiuid flowing therein and to yieldingly respond to sudden surges orf pressure therein, the mean pressure in the pipe being subject to gradual variations, a penforated mandrel encircling said first sleeve and having a plurality of throttling orifices, a second resilient fluid-impervious sleeve member encircling said mandrel and defining with said first sleeve a chamber wherein such pressure surges effect fiow of fluid in the chamber through said mandrel and yielding response in said second sleeve, cushioning compartment means encircling said second sleeve for maintaining `gas under pressure to dampen such pressure surges, a source of gas under pressure, sensing means connected to the pipe li-ne for sending a fiuid pressure signal responsive to pressure in the pipe line, reservoir means delaying and idampening the fluid pressure signal from said sensing means and sending a dampened Ifluid pressure signal, and control means connected to said source of :gas under pressure and actuated by said dampened fluid pressure signal for maintaining the gas pressure in said compartment substantially equivalent to the mean pressure in the pipe line.

5. A surge ldampening device for use in a pipe li-ne to minimize surges of pressure therein, said device comprising, in combination, a Ifirst resilient fluid-impervious sleeve member adapted to be mounted in said pipe line to rliorm a continuation thereof directly exposed to fluid flowing therein and to yieldingly respond to sudden surges of pressure the ein, the mean pressure in the pipe being subject to :gradual variations, a perforated mandrel having a plurality of throttling orifices encircling said first sleeve, a second resilient fluid sleeve member encircling said mandrel and defining with said first sleeve a chamber wherein such pressure surges effect flow of iluid in the chamber through said mandrel and yielding response in said second sleeve, cushioning compartment means encircling said second sleeve dor maintaining gas under pressure to dampen such pressure surges, a source of -gas under pressure (for said cushioning compartment, fluid pressure sensing means dor connection to said pipe to transmit a response to variations in the mean pressure in the pipe Iwhile dampening out response to such pressure surges, a reservoir receiving fluid pressure signals from said fluid pressure sensing means and sending out dampened fluid pressure signals and control valve means for said source responsive to the dampened fluid pressure signals transmitted by said sensing means via said reservoir for maintaining the -gas pressure in said compartment substantially equivalent ,to the rnean pressure in the pipe.

6. A surge dampening device for use in'la pipe line to minimize surges of pressure therein, said device comprising, in combination, a first resilient fluid-impervious sleeve member adapted to be mounted in said pipe line to form a continuation thereof directly exposed to fluid fiovving therein land to yielding-ly respond to sudden surges of pressure therein, the mean pressure in the pipe being subject to gradual variations, `a perfo-rated mandrel having ia plurality of throttling orifices encircling said first sleeve, a second resilient iiuidJimpervious sleeve member encircling said mandrel and defining with said first sleeve a chamher wherein such pressure surges effect flow of fluid in the chamber through said mandrel and yielding response in said second sleeve, cushioning compartment means encircling said second sleeve for maintaining gas under pressure to dampen such pressure surges, a source of gas under lpressure for said cushioning compartment, sensing means connected to the pipe line rior sending a fiuid pressure signal responsive to pressure variations in the pipe line, reservoir means ldelaying and dampening the fiuid pressure signal from said sensing means and sending a dampened fluid pressure signal 'and valve means in control of said source for communicating `gas pressure to said compartment in response to variations in the dampened fluid pressure signal for maintaining the 'gas pressure in said compartment substantially equivalent to the mean pressure in the pipe.

7. A surge dampening device for use in a pipe line to minimize surges of pressure therein, said device comprising, in combination, concentric resilient fluid-impervious sleeves adapted to be mounted in said pipe line, the inner sleeve forming a continuation of the line directly exposed to fluid flowing therein and to yieldingly respond to sudden surges of pressure therein, the mean pressure in the pipe being subject to gradual variations, a perforated concentric mandrel Ihaving a plurality of throttling orifices interposed between said `sleeves and isolated from the pipe ui-d, cushioning compartment means encircling said concentric sleeves for exposing the extenior thereof to gas under substantially the mean pipe pressure to dampen such pressure surges, ia source of gas under pressure, a uid pressure reservoir for dampenin-g abrupt Variations in uid pressure signals received thereby while responding with dampened -uid pressure signals to signcant changes in mean fluid pressure in the signals received, means sensing pressure changes in said pipe line and imparting a fluid pressure signal to said reservoir in response to changes in the pipe line pressure, and a. control valve interconnecting said cushioning compartment yand said source of gas under pressure, said control Iv'alfve being actuated in response to dampened uid pressure signals received from said reservoir.

References Cited in the le of this patent UNITED STATES PATENTS 2,124,619 Kerr July 26, 1938 2,290,337 Knauth July 21, 1942 2,609,001 Hebard Sept. 2, 1952 2,838,073 Di Mlottia et al. June 10, 1958 2,875,787 Evans Mar. 3, 1959 2,878,835 Peterson Mar. 24, 1959 2,905,200 Guier et al Sept. 22, 1959 

3. A SURGE DAMPENING DEVICE FOR USE IN A PIPE LINE TO MINIMIZE SURGES OF PRESSURE THEREIN, SAID DEVICE COMPRISING, IN COMBINATION, A FIRST RESILIENT FLUID-IMPERVIOUS SLEEVE MEMBER ADAPTED TO BE MOUNTED IN SAID PIPE LINE TO FORM A CONTINUATION THEREOF DIRECTLY EXPOSED TO FLUID FLOWING THEREIN AND TO YIELDINGLY RESPOND TO SUDDEN SURGES OF PRESSURE THEREIN, THE MEAN PRESSURE IN THE PIPE BEING SUBJECT TO GRADUAL VARIATIONS, A PERFORATED MANDREL HAVING A PLURALITY OF THROTTLING ORIFICES ENCIRLING SAID FIRST SLEEVE, A SECOND RESILIENT FLUID-IMPERVIOUS SLEEVE MEMBER ENCIRCLING SAID MANDREL AND MAINTAINING SAID MANDREL IN A SEPARATE BODY OF FLUID, WHEREBY SUCH PRESSURE SURGES EFFECT FLOW OF FLUID IN SAID BODY THROUGH SAID MANDREL AND YIELDING RESPONSE BY SAID SECOND SLEEVE, CUSHIONING COMPARTMENT MEANS ENCIRCLING SAID SECOND SLEEVE FOR MAINTAINING GAS UNDER PRESSURE TO DAMPEN SUCH PRESSURE SURGES, A SOURCE OF GAS UNDER PRESSURE, SENSING MEANS CONNECTED TO THE PIPE LINE FOR SENDING A FLUID PRESSURE SIGNAL RESPONSIVE TO PRESSURE IN THE PIPE LINE, RESERVOIR MEANS DELAYING AND DAMPING THE FLUID PRESSURE SIGNAL FROM SAID SENSING MEANS AND SENDING A DAMPENED FLUID PRESSURE SIGNAL, AND A CONTROL VALVE FOR SAID SOURCE RESPONSIVE TO THE DAMPENED FLUID PRESSURE SIGNAL FOR MAINTAINING THE GAS PRESSURE IN SAID COMPARTMENT SUBSTANTIALLY EQUIVALENT TO THE MEAN PRESSURE IN THE PIPE. 